1. Field of the Invention
The present invention relates to a coupler fixing structure for a modular wiper apparatus which may be installed in a vehicle such as a passenger car, a bus or a truck.
2. Description of the Related Art
A conventional modular wiper apparatus of the above-described type comprises a wiper motor, a link mechanism and wiper shafts, each of these constituents being integrally mounted to a relatively large bracket comprising an aluminum die-casting. Such an apparatus, however, entails the problem that the apparatus is heavy. In order to make the apparatus light and compact, it has been proposed to use a channel-type frame having a substantially U-shaped cross-section to link together a first bracket to which a wiper motor is mounted and a second bracket to which a wiper shaft is mounted.
In an apparatus having such linkage, the wiper motor is supplied with electricity through a circuit provided by coupling a motor-side coupler connected with leads led from the motor with a power-source-side coupler. When the couplers are being coupled with each other the leads may be forcibly extended if this operation is performed with the power-source-side coupler alone being held in place while the motor-side coupler is not held in place. In such case, there is the risk of the leads being broken or their connection with the coupler being damaged. In order to avoid these risks, it is necessary to support and fix in place the motor-side coupler. However, if the position of this fixing is located on the side of the associated driven body, such as the vehicle body, that requirement means that, when the modular wiper apparatus is being assembled onto the driven body, the motor-side coupler must also be supported and fixed in place on the driven body. In such case, therefore, the efficiency of the assembly operation is lowered.
In view of the above point, the motor-side coupler may be supported and fixed in position in the modular wiper apparatus per se. However, if the position of this supporting is located on the first bracket, the motor-side coupler will be located too close to the wiper motor to be uninfluenced by the motor, a heat-generating body. In addition, the motor-side coupler at such a location may interfere with swinging wiper links. Accordingly, it is necessary to provide measures against the above risks. With a view to avoiding the risks, it has been proposed to cause the frame to support the coupler. In a conventional arrangement of this kind, mounting holes are formed in the frame, and engagement projections, provided on the coupler and having pointed ends, are inserted into and engaged with the mounting holes in such a manner as to be prevented from disengagement. With this arrangement, however, since the mounting holes have to be formed in the frame, the strength of the frame itself is reduced. In order to compensate for this reduction, the frame must have a thick wall. This requirement causes other problems. One of them is that the requirement contradicts the original intention of making the wiper apparatus light.